Does Habitat Restoration Increase Coexistence of Native Stream Fishes with Introduced Brown Trout: A Case Study on the Middle Provo River, Utah, USA

Mark Belk,Brock Mcmillan,Craig Ellsworth,Eric Billman

doi:10.3390/w8040121

Abstract

Restoration of altered or degraded habitats is often a key component in the conservation plan of native aquatic species, but introduced species may influence the response of the native community to restoration. Recent habitat restoration of the middle section of the Provo River in central Utah, USA, provided an opportunity to evaluate the effect of habitat restoration on the native fish community in a system with an introduced, dominant predator—brown trout (Salmo trutta). To determine the change in distribution of fish species and community composition, we surveyed 200 m of each of the four study reaches both before restoration (1998) and after restoration (2007 and 2009). Juveniles and adults of six native species increased in distribution after restoration. The variation in fish community structure among reaches was lower post-restoration than pre-restoration. Overall, restoration of complex habitat in the middle Provo River led to increased pattern of coexistence between native fishes and introduced brown trout, but restoration activities did not improve the status of the river’s two rarest native fish species. Habitat restoration may only be completely successful in terms of restoring native communities when the abundance of invasive species can be kept at low levels.

Highlights

Habitat restoration has become the dominant conservation activity in response to anthropogenic disturbance and degradation of streams and rivers, and is often a key component in the conservation plan of native aquatic species [1,2,3]
Recent habitat restoration of the middle section of the Provo River in central Utah, USA provided an opportunity to evaluate the effect of habitat restoration on the native fish community in a system with an introduced, dominant predator—brown trout (Salmo trutta)
To determine changes in distribution we compared the number of reaches occupied prior to restoration to the number occupied after restoration for each species age class. Both adult and juvenile brown trout and adult and juvenile mottled sculpin were found in all four study reaches prior to restoration

Summary

Introduction

Habitat restoration has become the dominant conservation activity in response to anthropogenic disturbance and degradation of streams and rivers, and is often a key component in the conservation plan of native aquatic species [1,2,3]. The underlying assumption is that native aquatic species will benefit from the restored habitat and their populations will increase such that, after some initial time period, the native community of aquatic organisms will re-establish. Under this assumption, success of habitat restoration projects is usually defined as an increase in species richness, ecological diversity, or population abundances. Success of habitat restoration projects is usually defined as an increase in species richness, ecological diversity, or population abundances Changes in these metrics may be determined by multiple factors that may or may not be related to the habitat restoration, and all species and communities may not respond in a similar way [7].

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